Adds vulnerability scans with Trivy and Pull Request handling for SCM-Manager

Adds

• SCMManager for handling of Pull Requests (#50) and
• findVulnerabilitiesWithTrivy() for scanning Images with Trivy (#52, #53)

Upgrades

• Maven and Maven Wrapper and sets output to verbose (#51)

Extensions to Git and Docker

Adds

• Git.areChangesStagedForCommit() and
• Docker.Image.repoDigests()

Fixes

• Exception when using Docker.Image.push() and tag(): Scripts not permitted to use field
org.jenkinsci.plugins.docker.workflow.ImageNameTokens tag
• SonarQube: "Malformed key for Project" when not using branch plugin. " because this broke the built.

Remove env var DOCKER_HOST for Docker.mountDockerSocket

Remove env var DOCKER_HOST for Docker.mountDockerSocket.

Checking /var/run/docker.sock is the default anyway.
The env var causes an issue with spring boot maven plugin when running maven inside a container:
https://github.com/spring-projects/spring-boot/issues/22300

Unfortunately, unsetting the var with "withEnv(['DOCKER_HOST='])" does not work, but setting an env var would work.

So we remove the env var here, if anyone should need it (even though it's the default behavior!) it can just be set using
"withEnv(['DOCKER_HOST=unix:///var/run/docker.sock'])".

Fix Maven.evaluateExpression() not using repo credentials

Fix Maven.evaluateExpression() not using repo credentials.

Failed e.g. when querying something from a POM using a parent or dependency from a private repo.

Improve Docker.installDockerClient()

1.44.0

   1.44.0

GitFlow, Changelog, GitHub releases, more Git functionality

1.43.0

Merge pull request #32 from cloudogu/feature/30_release_process_funct…

Git.pushAndPullOnFailure() and Retry on all error codes

Note: This version accidentally breaks backward compatibility with git.push().

This will be fixed in the next version.
It affects all calls to git.push that don't add a remote but add multiple arguments, e.g.
git.push ('master develop') with the legacy behavior of git.push this would result in git push origin master develop, but with this version this results in git push master develop which is likely to fail.
See also #44.

git.pull()

Merge pull request #41 from cloudogu/feature/git_pull

Implements git.pull()

Git.merge() with configurable author and email

Merge pull request #40 from cloudogu/feature/merge_with_author

Adds merge with configurable author and email

SonarQube timeout can be configured

Merge pull request #39 from cloudogu/feature/sonar_configurable_timeout

Make SonarQube timeout configurable